An endoscope is a well-known optical system for evaluation of internal organs that was disclosed and claimed in U.S. Pat. No. 3,449,037 to C. J. Koester. Currently used fiberoptic endoscopes are comprised of many lenses mounted in a flexible tube to relay an image from inside a body cavity for viewing by a physician for diagnosis or manipulation inside cavitary spaces. Endoscopic ultrasound (EUS) is a device that combines endoscopy and ultrasound to image the gastrointestinal wall and surrounding structures. The first prototype for human use was developed in 1980, and several generations of echoendoscopes have been developed since then. In the 1990 the capability of obtaining tissue samples by this method resulted in further applications of this test to sample internal structures and organs. The ultrasound transducer is positioned at the tip of endoscope and the key components of the transducer are the piezoelectric crystals that vibrate to produce ultrasonic waves. The ultrasonic waves then travel through gastrointestinal lumen to its wall and beyond the visceral wall into the surrounding organs and the reflection of these ultrasound waves will be detected by the same crystals at the transducer and reconstruction of these reflections will result in creating a real time image of the gastrointestinal wall and its surrounding structures. The ultrasonic wave reflects from the surface of structures with different density and can pass very well through fluid containing and solid structures. However, air creates a barrier to ultrasonic wave passage and hampers obtaining ultrasonic images. Thus many attempts have been done to minimize the amount of interfering air between the transducer and the examining structure. These efforts could be seen in early patents by Yokoi in 1988 (Ultrasonic endoscope, U.S. Pat. No. 4,779,624), Wollschlager in 1992 (Ultrasound endoscope device, U.S. Pat. No. 5,105,819), Sakamoto in 1994 (Ultrasound transmission medium feed device for endoscopically inserting ultrasound probe, U.S. Pat. No. 6,004,273) and recently in the patent application by Nierich in 2007 (Transmission device for ultrasonic imaging system, publication No. 2007/0038109). In all of these, there is balloon at the end of the endoscope encloses the transducer and is filled with water to permit acoustic coupling between the transducer and the luminal wall or other gastrointestinal structures. This is particularly helpful in the part of gastrointestinal tract where the diameter of the lumen is small and the inflated balloon makes a good circumferential contact with the intestinal wall and thus creates a good acoustic coupling. In most parts of the gastrointestinal tract, however, the large diameter of the lumen and or the angle of the transducer in relation to the intestinal wall result in an inadequate contact between the transducer balloon and the intestinal wall and thus, the operators usually use water infusion to fill the region of the gastrointestinal tract with water and create acoustic coupling between the transducer and the examined structures. Unfortunately, the gastrointestinal tract is not a closed region and the infused water soon moves to other regions of the gastrointestinal tract. This can often result in poor image quality despite repeated infusion of water around the transducer. In addition, infusion of significant amount of water during the examination could result in untoward problems such as aspiration of the water into the patient's airway or overdistention of the gastrointestinal tract. To overcome this problem I have devised a device that creates a closed space around the ultrasound transducer using two balloons. Using two balloons in the gastrointestinal system has been suggested for the first time by Wilcox in 1987 (Double balloon nasobiliary occlusion catheter for treating gallstones and method of using the same U.S. Pat. No. 4,696,668) who used a double balloon catheter to make a closed space inside the bile duct to direct the chemicals used for lysing of gall bladder stone into the gall bladder and limit the exposure of the rest of the biliary system with this toxic agent. Later a two balloon approach was used on various endoscopic devices for assisting the movement of the endoscope deep down into the small intestine. The initial devices was proposed by Fujikura in 2005 (Insertion assisting tool for endoscope, publication No. 2005/0124856), Takano in 2005 (Endoscope apparatus, publication No. 2005/0165273), Machida in 2005 (Endoscope apparatus, publication No. 2005/0215855), and Yoshida in 2007 (Double-balloon endoscope system, publication No. 2007/0049797). In all these patents an overtube with a balloon is used to secure the position of the endoscope inside the gastrointestinal tract and the second balloon on the inserting tip of the endoscope is used to anchor and move the endoscope forward using alternating inflating and deflating of these two balloons.
Another device was described in U.S. Publication No. 2005/0107664 to Kalloo et al. which proposes an elongated dilating balloon serves to provide a uniform dilation of the stomach wall and two inflatable balloons affixed to the distal end of the overtube. Inflation of these two balloons can create a seal around the overtube while the overtube passes through a body cavity. The seal created by these two balloons can act like a barrier between two body cavities in his case between stomach and intra-abdominal cavity (peritoneum). In contrast to Kalloo's design, where two balloons are located at the distal end of the overtube, in the claimed device an inflatable positioning ring is affixed to the overtube at the distal end and an occlusion balloon is affixed a catheter at the distal end. The catheter passes through a passageway defined by the overtube. In Kalloo's device the balloons function to create a seal between two cavities (gastrointestinal lumen and peritoneal cavity). The present device however creates a sealed region in a single cavity (the gastrointestinal lumen). In Kalloo's device both balloons are in fixed position, but in the claimed design the positioning of the sealing devices is independent of one another. Also an elongated dilating balloon can be used to help to pass the overtube through a cut that is made in the gastrointestinal lumen. This dilating balloon passes through a passageway that is located within the endoscope and differs from the claimed occlusion balloon at the end of a catheter that passes through a passageway defined by the overtube. This gives this occlusion balloon freedom to move independently of the endoscope. In fact, there is no need to have an endoscope to deploy the occlusion balloon. The dilating balloon in Kalloo's device can only be introduced if the endoscope has already placed inside the overtube. In addition, in Kalloo's design, dilation balloon is just an accessory that is needed to temporarily dilate the opening of the incision in the stomach to help the passage of the overtube through the opening.
Another device was proposed application 20090227835 by Terliuc. This device is a flexible small overtube that is assembled on the distal shaft of an endoscope and then travels with the endoscope inside the body cavity. This overtube is fixed over the shaft of the endoscope and cannot be placed or moved independent of the endoscope in oppose to my invention which allows the endoscope to move freely and independently inside of the overtube. In fact, the endoscope can even be replaced with another endoscope while the overtube can be kept in its position. In addition, the overtube cannot be moved independent of the endoscope inside the body cavity since the proximal end of the said overtube is also inside of the body cavity while my claimed invention has a proximal end that is situated outside of the body cavity and can be moved independent of endoscope.
Another device is shown in Wenner et al. U.S. Pat. No. 6,440,061. Wenner et al. proposed an overtube with a catheter situated within a catheter tube and a free, independently positionable distal endportion that terminates in an inflatable occlusion balloon that exits from the side of the flexible overtube but not the end of the flexible overtube. Thus, it cannot create a liquid tight space at the end of the overtube. This is because the occlusion balloon in Wenner's patent is situated at the same side as the positioning balloon in relation to the end of the endoscope. In contrast, the present claims define an occlusion balloon and a positioning ring independently positioned on the proximal and the distal positions in relation to the end of the endoscope, thereby, creating a liquid tight space around the end of the endoscope. In fact, if the occlusion balloon of the Wenner's invention was to exit from the end of the flexible overtube and placed distal to the end of the endoscope the purpose of their invention, access of endoscope to the site of interest would be prevented since the endoscope view and access would have been blocked by the occlusion balloon. In addition, passage of a flexible tube into body cavity needs a rigid introducer sheath while in the current invention the overtube is being inserted into the body cavity over the endoscope and uses endoscope as the guide. The overtube also has a curved lower distal end and an angled tip, which is designed to work in an acute angled spot such as bile duct. This prevents this device to work similar to my device, which has a straight distal end in the gastrointestinal (GI) tract. And last but not least, there is no structure in overtube that can create a hydraulic seal between the endoscope and overtube. Thus, fluid can leak around the endoscope since device cannot create nor maintain a hydraulic sealed area distal to the tip of the overtube between the positioning balloon and the occlusion balloon similar to the current invention. Wenner's device can uses two occlusion balloons called first and second occlusion balloon that both can pass through overtube sheath ports to create a hydraulically sealed area between these two balloons but the hydraulically isolated region is not between an occlusion balloon and a positioning ring at the distal of the overtube. Not to mention that the device is not designed and cannot achieve hydraulically sealed region due to lack of any structure in the overtube to seal the endoscope within the overtube.
Yet another device was proposed by Chu et al. U.S. Pat. No. 5,916,145. In this device a flexible mesh overtube is inserted with the use of endoscope shaft as a guide and a distal housing that includes a suction chamber and an endoscope chamber on its distal end. Between the endoscope chamber and the suction chamber, there is a clear window which allows the endoscopic view of the area distal to the overtube through this window. The endoscope tip does not exit the distal end of overtube. This allows the endoscope to stay away from contaminants per inventors' point of view. The only access to the body cavity is through a passageway which allows using tools such as forceps or catheters distal to the tip of the overtube. A fundamental difference between this device and the current invention is that the endoscope exits the distal end of the overtube into body cavity in the current invention. In fact, for devices such as echoendoscope, it is essential for the distal tip of endoscope to touch the lining of the body cavity. In fact, the Chu overtube is not a through passageway for endoscope, and the entire mesh like mechanism works when the endoscope at the end pulls the distal end inside the body cavity by pushing force over its shaft. In addition, Chu et al. device does not have a catheter that terminates in an inflatable occlusion balloon as an integral part of the described overtube. There is mention of a possibility of using a dilation catheter that can be positioned in the distal end. The Chu et al. device fails to teach a structure that creates a seal inside the overtube and around endoscope since the distal end of endoscope at most abuts clear window or if there is no clear window, the tip of the endoscope cannot go beyond the overtube.
In the current invention, on the other hand the structure of the balloons and their functions are different.